High Temperature Exterior Building Products

ABSTRACT

An article suitable for outdoor construction applications is provided. The article includes an inner layer having a CPVC composition and an outer layer having a CPVC composition. An intermediate layer is sandwiched between the inner and outer layers. The intermediate layer is a PVC composition.

TECHNICAL FIELD

The invention relates generally to siding, trim, decking, fencing, roofing and other construction materials suitable for higher temperature applications than standard PVC applications.

BACKGROUND

Polyvinyl chloride (PVC), also known as vinyl, has become common in use as house siding, trim, decking and fencing. Because of its low cost and ease of installation, PVC has gained wide acceptance as a construction material. However, because of its inability to withstand higher temperatures, PVC siding is used mainly in cooler climates, such as the northern states of the U.S.A. The use of PVC is sometimes avoided in warmer climates, such as exist in the U.S. states of Florida and Arizona.

Recently, another problem has been found with PVC siding in cooler climates. More residential structures are being built with irregular exterior walls and closer to adjacent structures. This has led to structures having a problem with reflective heat causing the siding and trim to distort from the heat. The excess heat is generated as a result of the sun's rays shining on a window and being reflected to an adjacent wall of the same structure or a neighboring structure.

Also, PVC is normally sold in white or light pastel colors for construction applications. Dark colors, such as red, black, brown and the like absorb more energy from the sun and cause the temperature of the material to exceed the useable temperature of PVC. Consumers and builders would like the option of using dark colors for some structures.

Construction materials comprising PVC may benefit from improvements.

ASPECTS OF EXEMPLARY EMBODIMENTS

An exemplary embodiment includes an article suitable for outdoor construction applications that comprises an inner layer comprising a chlorinated polyvinyl chloride (CPVC) composition; an outer layer comprising a CPVC composition; and an intermediate layer sandwich between the inner and outer layers. An additional weather resistant cap layer may be included over the article outer layer. The intermediate layer comprises a PVC, or blended PVC composition. Other aspects of exemplary embodiments will be made apparent in the following Detailed Description of Exemplary Embodiments and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of exemplary embodiments, will be better understood when read in conjunction with the appended drawings. For the purpose of illustration, there is shown in the drawings certain exemplary embodiments. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown in the drawings or described herein.

FIG. 1 is a perspective view end portions of a siding substrate according to a first embodiment;

FIG. 2 is a sectional view of the siding substrate without the insulating material taken along line 2-2 of FIG. 1;

FIG. 3 is a sectional view similar to that of FIG. 2 of a siding substrate according to a second embodiment;

FIG. 4 a sectional view similar to that of FIG. 2 of a siding substrate according to a third embodiment; and

FIG. 5A-C are graphs showing the results of an Oven Sag Test for a sample of the siding substrate of the first embodiment and samples of other sidings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The articles of some exemplary embodiments are comprised of rigid thermoplastic materials with high heat distortion temperatures. Chlorinated polyvinyl chloride (CPVC) compositions may be used to make the articles by using an extrusion process.

A first exemplary embodiment comprises siding 10 used for buildings such as residential buildings and is depicted in FIGS. 1 and 2. As best seen in FIG. 2, the siding 10 comprises an inner layer 12 comprising a CPVC composition; an outer layer 14 comprising a CPVC composition; and an intermediate layer 16 sandwiched between the inner and outer layers 12, 14. The intermediate layer 16 of the exemplary embodiment comprises a polyvinyl chloride (PVC) composition. The exemplary CPVC material of the siding ranges from 9 to 75 wt. %, preferably 12 to 48 wt. %, and most preferred from 16 to 24 wt. % of the total weight of the CPVC inner and outer layers and the PVC intermediate layer. In one embodiment, the material of siding 10 of this embodiment contains about 16 wt. % CPVC and in another embodiment the material of siding 10 contains about 24 wt. % CPVC. The exemplary siding 10 also includes slots 18 formed at a hem 20 of the siding 10 that are used for hanging the siding. The siding may include an optional strip 28 for interlocking with a subsequent piece of siding (such as 10 is shown). The siding may also have an insulating member 22 such as foam adhered to the inner layer 12 by adhesive material between the insulating member 22 and the innermost layer 12, and/or a weather resistant cap layer 15 on top of the outer layer 14.

The CPVC compositions contain CPVC polymer (resin) along with various additives, which are described below. The CPVC resin constitutes at least 50% by weight of the CPVC composition as these are rigid compositions. CPVC compositions are available commercially worldwide from a variety of sources, including Lubrizol Advanced Materials, Inc. of Cleveland, Ohio U.S.A.

CPVC for use in exemplary embodiments may be prepared by the post-chlorination of suspension or mass polymerized PVC. Suspension polymerization techniques may be of the type described in the Encyclopedia of PVC, pp. 76-85, published by Marcel Decker, Inc. (1976), for example.

CPVC is obtained by chlorinating homopolymers or copolymers containing less than 50% by weight of one or more copolymerizable comonomers. Suitable comonomers for vinyl chloride include acrylic and methacrylic acids; esters of acrylic and methacrylic acid, wherein the ester portion has from 1 to 12 carbon atoms, for example, methyl-, ethyl-, butyl-, ethylhexyl acrylates and the like; methyl-, ethyl-, butyl methacrylates and the like; hydroxyalkyl esters of acrylic and methacrylic acid, for example, hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate and the like; glycidyl esters of acrylic and methacrylic acid, for example, glycidyl acrylate, glycidyl methacrylate and the like; alpha, beta-unsaturated dicarboxylic acids and their anhydrides, for example, maleic acid, fumaric acid, itaconic acid and acid anhydrides of these, and the like; acrylamide and methacrylamide; acrylonitrile and methacrylonitrile; maleimides, for example, N-cyclohexyl maleimide; olefin, for example, ethylene, propylene, isobutylene, hexene, and the like; vinylidene halide, for example, vinylidene chloride; vinyl ester, for example vinyl acetate; vinyl ether, for example methyl vinyl ether, allyl glycidyl ether, n-butyl vinyl ether and the like; crosslinking monomers, for example, diallyl phthalate, ethylene glycol dimethacrylate, methylene bis-acrylamide, tracrylyl triazine, divinyl ether, allyl silanes and the like; and including mixtures of any of the above comonomers. Comonomers as well as crosslinking comonomers are preferably absent. That is, preferred are homopolymers and uncrosslinked CPVC polymers.

The molecular weight as measured by I.V. of precursor polyvinyl chloride for the CPVC polymer will range from about 0.4 to about 1.6, preferably 0.5 to 1.2 and most preferably from about 0.7 to 1.0 I.V. The inherent viscosity is a representative measure of the molecular weight of a polymer and is obtained in accordance with ASTM procedure No. D-1243-66. The choice of molecular weight is made by considering the shape and intricacy of the profile, the processing conditions and the physical property balance desired. If the molecular weight is too low, there may be insufficient melt strength and the dimensional stability of the hot extrudate will suffer, and if the molecular weight is too high, the compound may not be processable under the desired conditions. Acceptable results are obtained under a variety of conditions and cross-sectional shapes using an I.V. of the PVC precursor of about 0.85 to 0.95.

Chlorination of PVC can be carried out to obtain a chlorinated base polymer having higher than 57 percent by weight chlorine up to about 74 percent by weight based upon the total weight of the polymer. However, in practice, the use of a major amount of CPVC having a chlorine content of greater than 65% weight and up to 74% is preferred, and more preferably from 66% to about 70% chlorine.

The preferred method of post-chlorination is by the aqueous suspension chlorination method. There are considerations relative to this method wherein the preferred mode of chlorination employs a relatively concentrated aqueous suspension of the precursor PVC. The most preferred method results in a CPVC resin having a density which does not deviate more than about 20 percent from the mean density, and a surface area which does not deviate more than 30 percent from the mean surface area is more desirable. A concentration of about 15 to about 35 weight percent of solids in the suspension is preferred. Generally, a concentration of the suspension higher than the specified range results in less uniform chlorinated product, while concentrations below 15 percent yield uniform product, but are not as economical. By “aqueous suspension” of PVC base polymer, we refer to a slurry-like mixture of base polymer macrogranules suspended in water. This process is particularly directed to a batch process.

It is desired that oxygen be removed from the aqueous suspension before chlorination is initiated. This may be assisted with agitation. Heating as may be required is preferably done after Cl₂ is sparged into suspension from a liquid Cl₂ cylinder until the pressure in the reactor reaches about 25 psig, at which point the suspension is saturated with Cl₂. It is preferred that this pressure be somewhat higher, that is, in the range from about 35 psig to about 100 psig, to get the optimum results, though a pressure as low as 10 psig and higher than 100 psig may be employed. The amount of Cl₂ charged to the reactor is determined by weight loss in the Cl₂ cylinder. The reactor is preferably brought up to a “soak” temperature in the range from about 60° C. to about 75° C. at which soak temperature the suspension is maintained under agitation for a soak period in the range from about 1 minute to about 45 minutes. Excessive pressure adversely affects the porosity of the macrogranules to the detriment of the stability of the chlorinated product.

It is desirable to complete the chlorination reaction under photo-illumination, preferably with ultraviolet light, or the desired conversion of base polymer to chlorinated base polymer product may not occur. Chlorination proceeds at a rate which depends upon the pressure and temperature within the reactor, higher rates being favored at higher temperature and pressure. It is most preferred to adjust the soak temperature, the mass of resin, and the level of photo-illumination so that the temperature is “ramped” by the heat of reaction until it levels off at a finishing temperature of about 100° C. After chlorination has proceeded to the desired degree, the suspension is preferably not cooled but dumped to be centrifuged and the chlorinated polymer freed from the aqueous phase, after which HCl is removed from the product, preferably by neutralizing with an aqueous solution of an alkali metal hydroxide. The product is then washed with water to free the chlorinated polymer of residual alkali, and dried, except that the temperatures at which the operations are carried out may be in the range from about 60° C. to about 100° C., which may be somewhat higher than conventionally used.

The rigid CPVC compositions contain various other ingredients, in addition to the CPVC polymer, to enhance processing and performance of the articles. Ingredients such as heat stabilizers, impact modifiers, processing lubricants, antioxidants, antistats, processing aids, fillers, fibers and coloring pigments can be used in the CPVC compositions of exemplary embodiments. A desirable additive in some embodiments is chlorinated polyethylene.

The chlorinated polyethylene (CPE), when used in the CPVC compositions of the multi-layer article, has a specific gravity of from about 1.13 to 1.4, preferably about 1.16, a residual crystallinity of from about 0 to about 25%, preferably 0 to 10%, and a chlorine content from about 25% to about 45%, preferably 35% to 44%. The chlorination can be either homogeneous or heterogeneous preferably to a small extent. Surface appearance of extrudates depended on CPE molecular weight and polydispersity as measured by gel permeation chromatography and on the extrusion conditions used. Chlorination methods for CPE include aqueous suspension, solution, or gas phase methods, with the preferred method by way of suspension chlorination. CPE is commercially available from numerous sources such as Dow Chemical Inc. When CPE is used, the amount of CPE in the CPVC compositions present ranges from about 10 to about 30 parts per 100 parts by weight (phr), preferably from about 12 to about to 25 phr, still more preferred are levels from 15 to 25 phr of CPVC resin. The particular combination of CPVC and CPE in exemplary aspects will be described below.

The core/shell type impact modifiers can be present in the CPVC compositions. These include acrylonitrile butadiene styrene terpolymers (ABS), methacrylate, acrylonitrile, butadiene, styrene (MABS) polymers and methacrylate butadiene styrene polymer (MBS). Other impact modifiers are disclosed in Plastics Compounding, November/December, 1983: “Update: Impact Modifiers for Rigid PVC,” by Mary C. McMurrer. Various commercial MBS grades include Paraloid® KM-653, BTA-733 from Rohm and Haas, or Kanegafuchi Inc. B-56 and B-22; Commercial polyacrylate impact modifiers include KM®-323B, and KM®-330, from Rohm and Haas, Inc.; ABS grades are commercially available from GE Plastics, Inc, for example, Blendex® 338.

Thermal stabilizers are employed in the compounds herein and can be selected from various organic compounds. Suitable tin stabilizers include tin salts of monocarboxylic acids such as stannous maleate. Examples of tin stabilizers include without limitation: alkylstannoic acids, bis(dialkyltin alkyl carboxylate)maleates, dialkyltin bis(alkylmaleates), dialkyltin dicrotonates, dialkyltin diolates, dialkyltin laurates, dialkyltin oxides, dialkyltin stearates, alkylchlorotin bis(alkylmercaptides), alkylchlorotin bis (alkylmercaptopropionates), alkylthiostannoic acids, alkyltin tris(alkylmercaptides), alkyltin tris(alkylmercaptoacetates), alkyltin tris(alkylmercaptopropionates), bis [dialkyl(alkoxycarbonylmethylenethio)tin] sulfides, butyltin oxide sulfides, dialkyltin bis(alkylmercaptides), dialkyltin bis(alkylmercaptoacetates), dialkyltin bis(alkylmercaptopropionates), dialkyltin β-mercaptoacetates, dialkyltin β-mercaptoacetates, dialkyltin β-mercaptopropionates, dialkyltin sulfides, dibutyltin bis(i-octyl maleate), dibutyltin bis(i-octyl thioglycolate), dibutyltin bisthiododecane, dibutyltin β-mercaptopropionate, dimethyltin bis(i-octyl thioglycolate), dioctyltin laurate, methyltin tris(i-octyl thioglycolate). Examples of a commercially available tin stabilizer are Mark 292 and Mark 1900 stabilizers from Chemtura Chemical and Thermolite 31 stabilizer from Arkema. Tin compounds are generally used at from 1 to 5 phr (parts by weight per 100 parts by weight of CPVC resin), preferably about 2.0 to 4.0 phr.

Secondary stabilizers may be included, if desired, but are not necessary. Examples of secondary stabilizers include metal salt of phosphoric acid, polyols, epoxidized oils, and acid acceptors which are not detrimental to the base CPVC resin used. The secondary stabilizers can be used by themselves or in combinations as desired. Specific examples of metal salts of phosphoric acid include water-soluble, alkali metal phosphate salts, disodium hydrogen phosphate, orthophosphates such as mono-, di-, and tri-orthophosphates of said alkali metals, alkali metal polyphosphates, -tetrapolyphosphates and -metaphosphates and the like. Polyols such as sugar alcohols, and epoxides such as epoxidized soya oil can be used. Examples of possible acid acceptors include potassium citrate, aluminum magnesium hydroxyl carbonate hydrate, magnesium aluminum silicates and alkali metal alumino silicates. Examples of magnesium aluminum silicates are molecular sieves such as, for example, Molsiv® Adsorbent Type 4A from UOP. Examples of alkali metal alumino silicates are zeolites such as CBV 10A Zeolite Na-Mordenite by Synthetic Products Co. The most preferred secondary stabilizer is disodium hydrogen phosphate (DSP) and is used by treating the CPVC resin. Typical levels of secondary stabilizers can range from about 0.1 wt. parts to about 7.0 wt. parts per 100 wt. parts CPVC polymer (phr).

In addition, commercially available antioxidants are used such as phenolics, BHT, BHA, various hindered phenols and various inhibitors like substituted benzophenones.

Other auxiliary components are contemplated. Antistats may be used and are commercially available under the Glycolube® trademark of Lonza Corp. Exemplary lubricants are the various hydrocarbons, such as paraffins, paraffin oils, low molecular weight polyethylene, oxidized polyethylenes, fatty acids and their salts such as stearic acid and calcium stearate, fatty alcohols such as cetyl, stearyl, or octadecyl alcohol; metal soaps such as calcium or zinc salts of oleic acid; fatty amides of organic acids such as stearamide, ethylene-bis-stearamide; preferred fatty esters and partial esters such as butyl stearate, polyol esters such as glycerol monostearate, hexaglycerol distearate; and fatty ester waxes such as stearyl esters. The most preferred lubricant is oxidized polyethylene. Henkel Co. produces a variety of preferred fatty ester formulations under the Loxiol® mark. Combinations of internal and external lubricants may also be used. Lubrication of the CPVC polymer compounds may involve several lubricants combined in variations. The total amount of lubricant may vary in some embodiments generally from about 2 to 10 phr, preferably from 2 to about 6 phr.

Adjustment of melt viscosity can be achieved as well as increasing melt strength by optionally employing commercial acrylic process aids such as those from Rohm and Haas under the Paraloid® Trademark, for example, Paraloid® K-120ND, K-120N, and K-175.

Exemplary fillers for both the CPVC layer and PVC layer are optional and include clay, wollastonite, mica, barytes, calcium carbonate, talc and silica including precipitated silicas, silica gels, metallic silicates, pyrogenic or fumed silicas and the like. These have the general formulae: SiO₂, M_(n)(SiO₃)_(x). The values of n and x can vary with the oxidation state of the metal associated with the SiO₃ ion. The values n and x are usually integers from about 1 to about 4.

Preferred pigments are the various titanium dioxides (TiO₂) and carbon blacks which are commercially available. Preferred TiO₂ types are coated or uncoated, rutile titanium dioxide powder. An exemplary commercial grade is Ti-Pure® R-100 from E.I. DuPont De Nemours and Co. Inc. (DuPont). If used, pigments such as TiO₂ are present in an amount ranging from 1 to 25 phr, more typically 3 to 15 phr, and most typically from 3 to about 8 phr. Optional coloring pigments can be used.

Coloring pigments are used to impart the desired color of the CPVC composition. TiO₂ is the normal pigment to give a white color and carbon black is used to give a black color. Blends of color pigments are often used to achieve a color that is other than black or white. For example, a blend of TiO₂ and carbon black is used to obtain a grey color. Various other color pigments such as red, blue, green, yellow and brown are commercially available from companies such as Ferro and Clariant. The color pigments can be added to the composition as dry powders, liquid dispersions or as a concentrate in the form of a color masterbatch.

The CPVC compositions are prepared by compounding the ingredients together. The method of compounding preferably used is high intensity methods to uniformly mix and fuse the components into a homogeneous compound such as with a Banbury/mill, followed by sheeting, slitting or extrusion into pellets, or cubes. The differences in process handling of CPVC compared with polyvinyl chloride-based compounds relate mainly to the temperature and viscosity differences and care must be taken to avoid too much work and shear burning. In the preparation of compounds, the components can be combined and mixed with a Banbury and milled on a heated roll mill. The fused compound can be extruded and chopped into cubes. Alternatively, the components can be combined in a compounding twin screw extruder. The compounds are extruded into final form at conventional stock temperatures from about 175° C. to about 225° C. The components of the CPVC composition can also be blended together in powder form and the blended powder fed to an extruder.

The articles of exemplary embodiments can be of any color, but are particularly useful in dark colors. Certain PVC articles, such as house siding, are often only available in white and light pastel colors. This is because the dark colors, such as black, red, dark brown and the like absorb more heat from the sun and distort PVC articles. PVC articles can be used in cooler climates in light colors (white or pastel), but are not generally used in warmer climates, such as southern and southwest U.S. climates, nor is PVC commonly used for house siding or the like in dark colors, even in cooler climates. Typically, only the outer layer of CPVC composition would need to be colored as the inner layer is hidden in use and the intermediate layer of PVC is hidden in siding applications. However, for efficiencies in production, it may be advantageous to use the same CPVC composition for both the inner and outer layers.

It is customary to define color as a L value. L value is a scale of from 0 to 100. The color black would represent an L value of 0 and the color white would represent an L value of 100. When the term “dark colors” is used herein, it means the color has a L value of less than about 50, preferably less than about 40, and more preferably less than about 30.

The CPVC compositions of exemplary embodiments preferably have a high heat distortion temperature (HDT) as measured by ASTM D-648. The HDT of exemplary compositions is greater than about 180° F. (about 82.2° C.), greater than 190° F. (about 87.8° C.), desirably greater than 205° F. (about 96.1° C.), preferably greater than about 210° F. (about 98.9° C.), and more preferably greater than about 215° F. (about 101.7° C.). HDT of the composition can be varied by the chlorine content of the CPVC polymer. The higher the chlorine content, the higher the HDT. HDT of the CPVC composition can also be affected by the various compounding ingredients. Liquid or low molecular weight ingredients such as plasticizers, process aids and lubricants can lower the HDT and thus are used in certain exemplary embodiments in small amounts. The particular HDT of the composition used to make the articles will generally be selected based on the service temperature the article will experience in use. For example, an article of a dark color will commonly benefit from a higher HDT than a light color article used in the same climate and application. Articles, such as siding and trim for siding commonly benefit from a higher HDT when they are subjected to reflective heat as can occur from windows in adjacent walls or adjacent structures.

To form the CPVC composition into various articles of exemplary embodiments, the extrusion process may be used. The extruder is fed with the composition in either powder, cube or pellet form. The composition is melt processed and forced through a die into the desired shape of the article. The extruder characteristics applicable to melt processing of the CPVC compounds include: Extruder drive/gearbox capable of generating high torque at low rpm. Vacuum venting to remove volatile components, moisture and entrapped air. A barrel L/D of at least 16/1 for twin screw; generally at least 20/1 for single screw. Temperature controllers able to control within +/−5° F. or preferably +/−2° F. Accurately controllable powder metering screw for powder compounds.

A ramped barrel temperature profile is advisable with a zone nearest the hopper set at 180° C. and the zone nearest the die at about 195° C. for 0.75 inch (about 19.05 mm) diameter screw. There can be used calibrating blocks at the exit end to assist in proper dimension sizing as the hot profile is cooled. Air streams can be used to improve heat loss, and for more close tolerances, vacuum water sizing devices can be used. The extent to which one chooses to employ calibrator blocks and air or water sizing will depend on dimension tolerances for the particular profile shape, the intended output volume of any one profile article and the number of different profiles made with a particular production set.

The CPVC composition described above is the preferred composition for making siding and siding trim components. For articles which are thicker, other CPVC compositions may be used and in some cases preferred. The CPVC composition used will vary depending on the requirements of the end use application. In some embodiments, the CPVC composition may be a CPVC based blend with other high heat plastics, such as styrenics. In alternate embodiments, at least one of the inner and outer layers may comprise a composition of a high heat plastic, such as, styrenics, for example, styrene-acrylonitrile copolymers (SAN), methyl-styrene-acrylonitrile copolymers (AMSAN), or blends thereof. The term “high heat plastics” as used herein refers to materials that can exceed 180° F. in continuous operating temperature.

When the exemplary article is a house siding or siding trim, the CPVC composition for each of the outer layer and inner layer may be extruded to a thickness of from about 2 to about 19 mils (about 0.05 to about 0.48 mm), preferably 3 to 10 mils (about 0.08 to about 0.25 mm) and more preferably 4 to 6 mils (about 0.10 to about 0.15 mm) The siding and trim thickness is typically about 30 to about 50 mils (about 0.76 to about 1.27 mm) and more typically 40 to 48 mils (about 1.02 to about 1.22 mm) The term “siding trim” as used herein has the customary industry meaning and includes trim pieces such as outside corners, inside corners, channels around windows and doors, and the like, used in conjunction with the installation of siding. The siding and trim of some embodiments can be thinner than PVC siding because the exemplary embodiments are able to withstand greater heat and are more resistant to deformations. The siding and trim can be embossed to provide a wood grain surface for aesthetic appeal. The siding and trim of some embodiments may be applied horizontally or vertically on a structure.

When articles of exemplary embodiments include decking and fencing, the extrusion may be thicker than that for siding because of the structural requirements. Decking and fencing will typically have a thickness of greater than 0.05 (about 1.27 mm) and preferably greater than 0.1 inch (about 2.54 mm) Decking and fencing are typically extruded with a cross section in a substantially rectangular shape and can have rounded corners to aid in the extrusion process. The term “rectangular shape” as used herein is intended to include rectangle shapes which have rounded corners. The rectangular shape can be hollow inside to save weight or can have reinforcing webs to add strength and rigidity. The extruded decking or fencing boards can also be filled with foam to add rigidity. Decking boards can also be embossed with a non-skid surface to provide more traction when wet. Decking materials may include the floor of the deck as well as supporting posts and rails, which can all be made from the exemplary CPVC compositions. Fencing may include the fence boards or rails as well as the posts. The decking and fencing articles of exemplary embodiments eliminate the need for painting or staining as well as the need to use treated lumber and the environmental and health risks associated with the use of pressure treated lumber.

As previously mentioned, exemplary embodiments including siding and trim may have an insulating layer 22. The insulating layer 22 may include a layer of polystyrene foam but could be other insulating materials, such as polyurethane foam. The insulating layer 22 is preferably bonded to the CPVC layer with a suitable adhesive 24 as illustrated in FIG. 1. A suitable adhesive for bonding CPVC to polystyrene foam is a moisture cured urethane, such as manufactured by Ashland Chemical Company of Columbus, Ohio U.S.A. and known as ISOGRIP® 3030D. Alternatively, heat and pressure sensitive adhesives can be used as well as latex based adhesives. Preferably, the adhesive remains flexible during use of the article.

The use of an insulating layer 22, such as foam, gives the siding and trim insulating properties to conserve energy. An insulating layer may also be used to make the siding or trim more rigid. Increased rigidity allows the CPVC layer to be thinner and aids in the installation of the articles to a structure. The siding and trim are attached to a structure by conventional means such as nails, screws, staples, adhesives or other fasteners.

To produce exemplary articles having an insulating layer 22, the CPVC composition may be extruded as described above. The insulating layer is formed to the desired size. The adhesive 24 is applied to the insulating layer or the CPVC extruded profile layer. The adhesive can be applied by roll coating, stitching, extruding, spraying or curtain coating. The adhesive can also be applied in the form of beads which cover only a portion of the CPVC layer. The extruded CPVC is applied to the insulating layer 22 with the adhesive between the layers to form the article. The articles may be made in conventional lengths, such as 10 or 20 feet (about 3.05 or 6.1 m), to facilitate storage and transport to a job site.

The intermediate layer 16 of PVC can be made from commercially available PVC compositions, including recycled material. The PVC compositions are available from several manufacturers, such as ShinTech and PolyOne. Preferably, a PVC composition used is one designed for siding applications. The PVC compositions designed for siding applications use the same PVC resin as described above for the PVC precursor resin used to make the CPVC resin. Also, similar additives, such as heat stabilizers, impact modifiers, flow aids, lubricants and the like, can be used as described above for CPVC. The PVC compositions can be made the same way as the CPVC compositions described above, except that PVC has a slightly lower processing temperature, usually about 10-30° F. The % of the CPVC layers in the composite siding herein are expressed in weight percent. This is slightly different from thickness percent, as CPVC compositions normally have a higher specific gravity than PVC, usually about 10 to 20% higher. If the PVC layer contains a large amount of heavy fillers, such as calcium carbonate or talc, it may have a higher specific gravity than the CPVC layers, as is well understood by those skilled in the art.

Embodiments that comprise siding 10 can be made in conventional widths such as from 4 to 10 inches (about 10.16 cm to about 25.4 cm) or can be made in thinner or wider widths. The addition of an insulating layer to provide added rigidity may allow the siding to be made wider than conventional siding, if desired. Wider widths can reduce labor in the installation phase of construction. Widths as wide as 12, 18, 24, 36 or 48 inches (30.48, 45.72, 60.96, 91.44, or 121.92 cm) can be made with the insulating layer 22 capped with CPVC. Siding trim pieces may also be made in standard widths, or wider or narrower in some embodiments.

The CPVC layer on the insulated siding and trim will preferably be from about 2 to about 19 mils (about 0.05 to about 0.48 mm), preferably 3 to 10 mils (about 0.08 to about 0.25 mm) and more preferably 4 to 6 mils (about 0.10 to about 0.15 mm) thick. The insulating layer is preferably a thickness of from about 0.1 to about 2.0 inches (about 0.254 to about 5.08 cm). PCT Patent Application WO 99/22092 describes a PVC siding product with a foam backing and U.S. Pat. No. 5,542,222 describes a corner post of PVC with a foam backing. The CPVC siding and siding trim components of this invention are made similar to those described in the two disclosures above with the exception that the PVC layer is replaced with two CPVC layers (inner and outer layers) and a PVC intermediate layer. The outer CPVC layer or all three layers can be in dark colors. U.S. Pat. No. 5,542,222 and PCT Patent Application WO 99/22092 are hereby incorporated in their entirety in this disclosure.

Cap layer(s) can also be applied to the CPVC outer layer to increase weather resistance. One or more cap layers can be used. For example, a thin cap layer of PVC can be applied to the CPVC layer. In place of a PVC containing cap layer, a cap layer of ASA (acrylonitrile-styrene-acrylate) can be used. The PVC or ASA cap layer may be about 3 to 10 mils (about 0.08 to about 0.25 mm) thick and can be co-extruded with the CPVC layer. Since the cap layer has a lower HDT than the CPVC layer, the cap layer is preferably thinner than the CPVC layer. In some embodiments, a further cap layer of a composition containing a fluoropolymer can be applied to the first cap layer or can be applied directly to the CPVC layer. The fluoropolymer cap layer may be about 1 mil to about 2 mils (about 0.03 to about 0.05mm) thick. The fluoropolymer cap layer can be pre-prepared and laminated to the CPVC or first cap layer or can be co-extruded directly onto the CPVC or first cap layer. The fluoropolymer containing cap layer may also contain a substantial amount of acrylic polymer in order to gain adhesion to the CPVC or first cap layer. A fluoropolymer containing cap layer and the ASA cap layer may have better weathering properties than the CPVC or PVC layer.

FIG. 3 shows a second exemplary embodiment. Similar reference numbers will be used for elements that are common with the first embodiment. This siding 100 comprises an inner layer 12 comprising a CPVC composition; an outer layer 14 comprising a CPVC composition; and an intermediate layer 160 sandwiched between the inner and outer layers 12, 14. This intermediate layer 160 comprises a semi-rigid material such as fiber cement composition. An adhesive layer (not shown) may be used between the intermediate layer 160 and the inner layer 12 and between the intermediate layer 160 and the outer layer 14.

FIG. 4 shows a third exemplary embodiment. Similar reference numbers will be used for elements that are common with the first embodiment. This siding 200 comprises an inner layer 12 comprising a CPVC composition; an outer layer 14 comprising a CPVC composition; and an intermediate layer 260 sandwiched between the inner and outer layers. The intermediate layer comprises a semi-rigid material such as PVC foam or CPVC foam.

EXAMPLE

Tests were performed on composite plaques (representing siding) of the exemplary embodiment and two other multi-layer (comparative) composite products. To form the composite plaques, three layer samples are put into a press cavity plate for thickness control. The press is set at about 380° F. (about 193.3° C.) with 1000 psi (about 6.89 MPa) low pressure for 6 minutes. The pressure is raised to 54 tons and held for 3 minutes. The obtained composite is then cooled under pressure. One of the comparative composite plaque products comprised a layer of PVC with only one layer of CPVC. The weight percentage of CPVC content in this comparative product was 24%. The other comparative composite plaque product comprised an inner layer comprising a PVC composition; an outer layer comprising a PVC composition; and an intermediate layer sandwich between the inner and outer layers. The intermediate layer comprised a CPVC composition. The weight percentage of CPVC content in this product was 60%. Samples of 0.125 inch (about 3.18 mm) thick for each plaque to be tested were taken.

One test was done using composite plaques comparing the Oven Sag at 180° F. (about 82.2° C.), 200° F. (about 93.3° C.), and 230° F. (about 110° C.) of the composite of the first embodiment with the two comparative above-mentioned other multi-layer composite siding products. The oven sag test does not use an actual sample of siding, but rather uses a plaque made up of layers of materials which would be used to make a siding product. The oven sag test correlates well with the actual siding product. The oven sag test looks at the sag of a sample bar under gravity load. One end of the bar is clamped while the other end is free to sag. By employing a range of temperatures, the temperature at which gross sag takes place can be found. Samples of 0.125 inches (about 3.18 mm) thick plaques for each composite to be tested were taken with a sag arm length set at 3¼ inches length (82.55 mm) The percent content of CPVC was varied for each composite product.

The results of the test for the two layer PVC/CPVC composite siding product with the CPVC layer on the bottom is shown in FIG. 5A. As seen in FIG. 5A, the two layer PVC/CPVC composite siding product with the CPVC layer on the bottom significantly improved sag resistance compared to the rigid PVC. As the CPVC content increased, the sag decreased and the sag resistance increased.

The results of the test for the three layer PVC/CPVC/PVC composite plaque product is show in FIG. 5B. This composite did not show bending after processing due to symmetry of the layers.

The results of the test for the three layer CPVC/PVC/CPVC composite plaque product of the exemplary embodiment is shown in FIG. 5C. This composite product performed the best of the three products tested in reducing sag at elevated temperatures even when used at low concentrations of CPVC. For example, with a CPVC content of 16% weight, this sample deflected less than 5 mm when the Oven Sag Test was performed on it at 180° F. (about 82.2° C.), 200° F. (about 93.3° C.), and 230° F. (about 110° C.). Hence, from the standpoint of sag resistance/stiffness retention at 180° F. temperature, the CPVC content can be as low as 16-24% weight. This low percentage of CPVC reduced the costs of the product and thus, made it the most economical choice among the three siding products tested. Also, the symmetrical placement of the layers prevents bending or distortion of the composite samples after processing and produces the flattest specimens.

In the foregoing description, certain terms have been used for brevity, clarity and understanding, however, no unnecessary limitations are to be implied therefrom, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the descriptions and illustrations herein are by way of examples and the invention is not limited to the exact details shown and described.

In the following claims, any feature described as a means for performing a function shall be construed as encompassing any means known to those skilled in the art to be capable of performing the recited function, and shall not be limited to the features and structures shown herein or mere equivalents thereof. The description of the exemplary embodiment included in the Abstract included herewith shall not be deemed to limit the invention to features described therein.

Having described the features, discoveries and principles of the invention, the manner in which it is constructed and operated, and the advantages and useful results attained; the new and useful structures, devices, elements, arrangements, parts, combinations, systems, equipment, operations, methods and relationships are set forth in the appended claims. 

What is claimed is:
 1. An article for construction applications comprising: a. an inner layer comprising a CPVC composition; b. an outer layer comprising a CPVC composition; and c. an intermediate layer sandwich between said inner and outer layers, the intermediate layer comprising a PVC composition.
 2. The article of claim 1 further including a cap layer adhered to the CPVC composition outer layer.
 3. The article of claim 1 wherein the CPVC composition is at least 16 weight percent of the material of the article.
 4. The article of claim 1 wherein said article includes a siding panel.
 5. The article of claim 1 wherein the CPVC composition has a heat distortion temperature greater than 180° F.
 6. The article of claim 1 and further including a layer of insulation foam adhered to the inner layer.
 7. The article of claim 1 wherein at least one of the inner layer and the outer layer has a thickness in the range of 2 to 19 mils.
 8. The article of claim 7 wherein at least one of the inner layer and the outer layer has a thickness in the range of 4 to 6 mils.
 9. The article of claim 1 wherein the outer layer is a dark color having an L value less than
 50. 10. The article of claim 1 wherein the intermediate layer comprises more than an insignificant amount of talc.
 11. The article of claim 1 wherein the article having a CPVC material content of 16 weight percent is deflected less than 5 mm in Oven Sag Tests performed at 180° F., 200° F., and 230° F.
 12. The article of claim 1 wherein the article has a thickness of from about 30 to about 50 mils.
 13. The article of claim 12 wherein the article has a thickness of from about 40 to about 48 mils.
 14. The article of claim 2 where said cap layer is selected from the group consisting of PVC, ASA, and fluoropolymer.
 15. The article of claim 14 wherein said cap layer comprises a fluoropolymer and has a thickness of from about 1 to about 2 mils.
 16. The article of claim 1 wherein at least one of the inner layer and the outer layer has a thickness in the range of from about 3 to about 10 mils.
 17. An article for construction applications comprising: a. an inner layer comprising a high heat plastic composition; b. an outer layer comprising a high heat plastic composition; and c. an intermediate layer sandwich between said inner and outer layers, the intermediate layer comprising a PVC composition.
 18. The article of claim 17 in which at least one of the high heat plastic compositions of a. or b. is a CPVC composition. 